"I very much hope that in the aftermath of this trial they are both able to arrive at some form of truce."

The court was told that Miss Williams had just sold her £200,000 Cambridgeshire home but would receive only £20,000 after paying debts to her building society and former solicitors.

Thomas Linden, for Lady Archer, then asked for an interim payment of £100,000 of the costs, the final level of which will be settled at a later hearing. But the judge rejected the request, saying: "The claimant is a person of extreme wealth. The defendant is on all evidence penniless."

He allowed, however, an interim order for the immediate payment of the £2,500 damages. The total amount for which Miss Williams is liable will be settled at the later hearing.

Miss Williams tried to use the Human Rights Act and the European Convention on Human Rights to support her case, but the judge said that both favoured Lady Archer's right to privacy as she was "not a public figure of the kind that merits close scrutiny".

He said that Lord Archer's "achievements and activities" had "brought her under the spotlight".

The judge said he was satisfied that Miss Williams had breached the confidentiality that was set out as an "express term" of her contract with Lady Archer.

"This must continue in force after the termination of employment. It would defeat the terms of contract if it fell away the moment the employee cleared her desk," he said.

The injunction prevents further disclosures about Lady Archer's medical treatment, including cosmetic surgery, financial and business affairs, home life, information from diaries, e-mails or correspondence, and anything to do with legal matters or home security. It also covers Lady Archer's sexual relationship with her husband.

After the case, Lady Archer released a statement welcoming the ruling. She said: "I am very pleased that the court has ordered a permanent injunction that protects me, my family, our friends and employees from further breaches of our confidence and violations of our privacy by Jane Williams.

"The judgment is a complete vindication of the action I started last year and I'm only sorry that the matter had to come as far as court to be resolved.

"The award of damages is in line with recent similar cases but damages were never a priority for me in this case."

Miss Williams gave a statement saying: "I'm reassured that the judge commented on my 13 years of trustworthy and loyal service.

"I feel I've been the victim of circumstances. The whole matter has taken a long time to come to trial and I was of course forced to defend myself.

"This was an important case. I'm very grateful to the legal team who have supported me but I'm devastated with the findings and the financial implications."

Miss Williams was Lady Archer's personal assistant for 13 years, until her dismissal in November 2001.